Arkansas cotton: rains welcomed, pests reported

Due to mid-June rains, Arkansas’ cotton crop — anywhere from bloom to just squaring — has shaken off lethargy, and producers have been able to cut back the use of irrigation pumps. That’s good news, but there still are things to watch for.

Cotton farmer with the ubiquitous small yellow flowers (plains coreopsis) edging their fields are likely seeing, or will see, plant bug damage. The flowers are often “absolutely loaded” with the pests, said Gus Lorenz at an IPM meeting south of Pine Bluff, Ark., on June 21.

To prove his point, the Arkansas Extension entomologist took a sweep net to a nearby ditch full of the flowers. After several sweeps, he paused to take a look. Plant bugs and other pests poured from the net — too many to count.

“There are a bunch of plant bugs on wild hosts currently. They’re staging to move into the cotton crop. Adults may move in and out of the cotton two or three times daily.

“We found out that you may sweep early in the morning and catch seven or eight plant bugs. Sweep the same area again at noon and you won’t catch anything. That means there’s a lot of movement in the field. It does make a difference what time of day you sample.”

To address this, Lorenz and entomologists from other Mid-South states have undertaken a time-of-day sampling study. They hope to have preliminary recommendations soon.

While plant bugs are plentiful they haven’t always required treatment.

“There are some cotton fields blooming in south Arkansas that haven’t received a plant bug application. Then, a quarter-mile down the road, there will be fields that have been sprayed two or three times. That pattern is being repeated everywhere.”

Don Plunkett, Jefferson County, Ark., Extension agent, said herbicide injury continues to hit fields. Holding up pictures of a pockmarked cotton field, Plunkett said the situation was self-inflicted.

“This grower’s bean crop was sprayed and there was 2,4-D involved. It messed up a bunch of cotton acres.”

Pointing to the photo, Plunkett said glyphosate drift injury can mimic injury from 2,4-D.

“That’s shown up in Altheimer, for example, where it appears the driver came to the end of a field. He had to slow down, cross the turn row and start back up. In each of the two fields, there’s quite a bit of this. So be aware glyphosate can cause what appears to be 2,4-D injury.”

Reporting comments from Cliff Coker, Arkansas Extension plant pathologist, Plunkett said if producers should check the root systems of soybeans in sandy fields that look to have a potash deficiency.

“Coker put in test plots in a Tucker field that, two years ago, was eaten up with cyst nematodes. Last year, that field was planted to grain sorghum. This year, it went back to soybeans and, apparently, cyst nematodes are eating the crop’s lunch. If you’ve got sandy fields that appear to have a potassium deficiency, there may be nematode pressure.”

Before the recent rains, Lorenz was very concerned with building numbers of spider mites.

“They’re still out there and we can find them, but they aren’t as big a threat as they were. A test not far from here had good populations building around Keo. Since the rains, those populations have dipped.”

In the short amount of time spent on the mite test, researchers found the best control product to be Kelthane. Zeal and Zephyr worked well, too.

“I could spend $9 per acre or $20 per acre. If you want to band the crop and get the cost down to $10, that’s fine. But you can band Kelthane and get the cost down to $4.50.

“For the first shot, to buy time, I think that’s the best program to go with. That’s what we’ve found in our studies. That way Zeal and Zephyr can be saved until you get in a bind later in the season.”

Aphid reports have been popping up and numbers appear to be building. To treat aphids, Louisiana recently received a Section 18 for Furadan.

“They felt their neonicotinoids — Centric, Trimax — were failing… But all those I’ve talked to (in south Arkansas) have told me they’re having no control troubles with neonicotinoids. And we’re not going after a Section 18 for Furadan until I hear something from folks that makes me feel we need one.

“Centric has provided us very good control. Trimax does okay and Intruder does very well on aphids. All of those products should provide the control we need.”

When walking fields, Lorenz and colleagues are beginning to kick up moths. Producers and consultants should begin watching for budworms and bollworms.

“I believe we’re on the front end of a significant egg lay. July 4 is when we normally get the big flight (in south central Arkansas), and I don’t think it’ll be any different this year. We’re right on target and expect this one to be pretty heavy. That’s based on relatively high numbers through the season thus far.

“If you’ve been holding off getting the Hi-boy ready to go, now’s the time to get it squared away.”

Lorenz has also been getting many calls from soybean producers on the white-fringed burrower bug.

“This insect isn’t causing any problems, and there’s not much cause for concern. But there are a ton of them out there.”

Stink bugs are also beginning to move into early-planted soybeans. They aren’t very serious now — most fields are around half threshold.

“But I promise you, when those beans get a little older, you’ll have to treat. Stink bugs are thick and have been since early on. This is a stink bug year.”

Rice stink bug numbers have also been extremely high.

“When the rice begins heading, watch out for them. I’ve seen more of those pests early season than I’ve ever seen before.”